Hierarchical planning architectures for mobile manipulation tasks in indoor environments

This paper describes a hierarchical planner deployed on a mobile manipulation system. The main idea is a two-level hierarchy combining a global planner which provides rough guidance to a local planner. We place a premium on fast response, so the global planner achieves speed by using a very rough approximation of the robot kinematics, and the local planner begins execution of the next action even without considering subsequent actions in detail, instead relying on the guidance of the global planner. The system exhibits few planning delays, and yet is surprisingly effective at planning collision free motions. The system is deployed on HERB, combining a Segway mobile platform, a WAM arm, and a Barrett hand. The navigation and manipulation components have been tested on the real robot, and the task of simultaneously approaching and grasping a bottle on a countertop was demonstrated in simulation.